The present invention relates generally to aerosol mounting cup closures having a valve staked into the pedestal portion thereof and, more particularly, to an improved mounting cup closure for an aerosol container.
In the filling of an aerosol container with propellant there are generally two systems employed. In one system, propellant is introduced into the container by passing the propellant under pressure between the bead of the container and the underside of the valve-bearing mounting cup closure. This system is commonly referred to as "under-the-cap" filling. In a single operation, the cup is lifted to create the filling space between the cup and the container bead and subsequently, after entry of the propellant, the mounting cup is crimped and sealed to the container bead. In a second system, the valve-bearing mounting cup is crimped and sealed to the container bead prior to the introduction of the propellant and the propellant is then introduced to the container by passing the propellant simultaneously through the valve and around the valve between the underside of the skirt of the mounting cup and the upper surface of the gasket obturating the valve stem orifice; this second system being commonly referred to as "pressure filling".
In pressure filling an aerosol container, a propellant filling head is advanced to a sealing position against the pedestal portion of the mounting cup. To generate a seal on the upper face of the pedestal and to withstand the force against the mounting cup and the concomitant breaking of the pedestal - filling head seal, an appropriate offsetting force must be applied against the force created by the advancing filling head. The stress on the mounting cup to unseat the filling head must be resisted so as to maintain the filling head - pedestal seal. If the seal is disengaged, propellant will flow, undesirably, external to the container.
Obviously, the disengagement of the seal between mounting cup and filling head during filling can result in economic disadvantages through the unwanted loss of propellant. Other economic losses attributable to the failed seal are also obvious; namely, the destruction of the valve and the need to remove the container bearing the product to be dispensed from the filling line. Because of the very large market for aerosol mounting cup closures and the very competitive pricing of valved mounting cups, it is important that the mounting cups be made as economically as possible and the above enumerated economic losses are undesirable.
A significant portion of the manufacturing costs of the valve mounting cups is the metal of the mounting cup. It is well appreciated by those skilled in the art, that a small saving in the amount of metal in each mounting cup will result in large savings to aerosol valve manufacturers due to the billions of mounting cups produced annually. Therefore, reduction in the thickness of the metal of the mounting cup while maintaining the strength of the mounting cup against the force imposed by the filling head is of economic importance. Conversely, an increase in strength, using the same thickness of metal, is also of great importance from the standpoint of permitting more rapid filling speeds.
The configuration of aerosol mounting cups conventionally used to close aerosol containers, the so-called one (1) inch mounting cups, comprises a raised central or pedestal portion having a central opening to receive a valve stem of the aerosol valve, a profile portion extending radially from the pedestal portion, a body portion extending upwardly from the outer terminus of the profile portion and a skirt portion extending from the body portion for receiving and affixing the mounting cup to the bead of the container.
This invention concerns a modification of the configuration of the profile portion of prior art mounting cups.
In the most common configuration of prior art mounting cups, the profile portion of the mounting cup has a substantially continuous conical profile angle as it extends from the profile portion contiguous to the body portion to the profile portion contiguous to the pedestal portion. In other prior art mounting cups the profile portion has a profile configuration with an upwardly, slightly bowed surface. In still other prior art cups, the profile portion is substantially flat or parallel to the horizontal axis of the cup. In the prior art mounting cups the profile configuration has a similar radius of curvature at the body/profile junction, i.e. the radius at the joinder of the body portion and the profile portion of the mounting cup. It is in this area that the forces generated by the downward motion of the filling head are concentrated.
It has been found that the configuration of the prior art profile portion does not provide the best profile configuration for resisting the force of the filling head during filling of the aerosol container with propellant in the pressure filling system. As a consequence there has been seal rupture during pressure filling. Moreover, due to the inability of the mounting cup to resist the advancing force of the filling head, the manufacturer has been frustrated in its attempts to reduce metal thickness and effect concomitant economies.